Saw something new (to me) today on a C5... Did EFI Live do this?

[Frost]

Hey guys...

While I am still puttering around with EFI Live and dragging my feet with buying the streams, my day to day work is with HPTuners.

I had a vette today that was previously street tuned (no wideband) with EFI Live. Besides being 10.0:1 (richer; that's the wideband's floor) until 4500 where it moved to about 11.0:1 at WOT, it ran and drove very well.

I had the owner drive me around the block beforehand because I wanted a scan. B2S1 was at 445-447mV the whole time (yes unhooked or dead) and not only did the car NOT code for it, B2 was TRIMMING in a fashion that so closely followed B1, it looks like the data was actually coming from the B1 sensor.

Is this really a "thing" ? :)

[5.7ute]

I noticed something similar when driving to Vic with another forum member.(2003 VY commodore using 01290005 OS) One dead 02 sensor reading reference voltage & near matching STFT for both banks. Also no code was present.
We were using BIDI at the time playing with timing so I dont think I recorded the log. I will have to have a look.

[joecar]

If B2S1 was flatlined then the trimming couldn't have been coming from B2S1...

Is this one of the PCM's failover modes...?

Was trimming for B2 coming from B1S1 or from B2S2...?!?

I've heard of the PCM using BxS2 to trim in place of a flatlined BxS1 (on the same bank).

If there's no codes, then there has got to be some flag to indicate this...

Did you get a log of all four sensor voltages HO2Sxx and LTFT's/STFT's...?

[Blacky]

Try logging the PID SAE.FUELSYS.

It returns the following data for each bank:
1 OL "Open Loop, Not ready for Closed"
2 CL "Closed Loop, Using O2 Sensor"
4 OL-Drive "Open Loop, Driving Conditions"
8 OL-Fault "Open Loop, Detected Fault"
16 CL-Fault "Closed Loop, Faulty O2 Sensor"

The CL-Fault option is where the PCM will use the data from the remaining good O2 sensor to trim both banks.

Regards
Paul

[joecar]

Note to self: see if I can make CL-Fault happen.

[mr.prick]

I tripped off an O2 code the other day (forget which one) and this set the
PCM onto open loop.

Maybe the rich AFR is from the WBO2 or VE/MAF being off. :nixweiss:

[Frost]

I noticed something similar when driving to Vic with another forum member.(2003 VY commodore using 01290005 OS) One dead 02 sensor reading reference voltage & near matching STFT for both banks. Also no code was present.
We were using BIDI at the time playing with timing so I dont think I recorded the log. I will have to have a look.


I have multiple logs in the 'other' format :) This was 2000 Cs A4 9381344 OS

No related DTC was present. Actually, none were at ALL.



Try logging the PID SAE.FUELSYS.

It returns the following data for each bank:
1 OL "Open Loop, Not ready for Closed"
2 CL "Closed Loop, Using O2 Sensor"
4 OL-Drive "Open Loop, Driving Conditions"
8 OL-Fault "Open Loop, Detected Fault"
16 CL-Fault "Closed Loop, Faulty O2 Sensor"

The CL-Fault option is where the PCM will use the data from the remaining good O2 sensor to trim both banks.

Regards
Paul


Thanks! I should have bought your setup last fall/winter when I had some time. I am short on the time that I want for reading and getting a feel for things.

Why didn't it set a DTC and if it did, would it then fail to OL? Any idea of the difference in failure criteria?

I've never seen or heard of this before; it's nice to learn something new :) Thanks for taking the time out to post.



I tripped off an O2 code the other day (forget which one) and this set the
PCM onto open loop.....

This is what I expected to happen as well.

Joecar: [assuming similarities] unhook a sensor; that's what it looked like in the log.

[joecar]

I'll try unhooking the NBO2 and a few things with the wideband's NBO2 emulator mode.


Short on time:

If there's anything we can answer in a more concise manner, please feel free to ask, we'll do our best.

I have some summary/cheat sheets on my profile page if they help, you already know all that stuff... also follow link in my sig.

:)